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[MUSIC] The faucet has a slow leak. 
It's dripping. 

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How much water is being wasted? 
Let's find out. 

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Now, I'm going to start the timer and see 
how full the measuring cup is after, say, 

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three minutes. 
[MUSIC] So, after three minutes of 

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dripping, the drip has put approximately 
13 milliliters of water into this 

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measuring cup. 
Here, I have a cube that holds one liter 

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of liquid. 
How long would it take our dripping 

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faucet that drips 13 milliliters per 
three minutes to fill this cube that 

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holds 1000 milliliters? 
[MUSIC] Alright. 

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It's been about 90 minutes. 
Let's see where we're at. 

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It looks like almost exactly 400 
milliliters. 

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So, we've collected some data and now, 
let's see if we can figure something out. 

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Alright. 
Here at time and time and water. 

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After three minutes, we found that 13 
milliliters of water are inside the 

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measuring cup. 
This tells us that the water is entering 

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the measuring cup at a rate of 13 
milliliters for three minutes, which is 

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equal to or approximately [SOUND] 4.3 
milliliters per minute. 

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Later, we checked it and we found that 
after 90 minutes, there were 400 

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milliliters in the cube this time. 
Well, this tells us since going from here 

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to here, we have a difference of 87 
minutes and going from here to here, we 

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have a difference of 387 milliliters, 
this gives us a new rate. 

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It says, that we have 387 milliliters per 
87 minutes and that's approximately 4.4 

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milliliters per minute. 
Aha. 

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This looks like it's linear growth. 
I know that the slopes are slightly 

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different but such a, such a small 
difference that if we plot it, it should 

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be linear. 
Now, at what time is there one liter of 

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water in the cube? 
That would be 1,000 [SOUND] milliliters. 

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At what time? 
So, we should use t for the variable 

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there. 
We have to solve the following equation. 

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We want 1000 / t to be approximately 
well, what's between 4.3 and 4.4? 

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4.35, okay? 
Ha, ha. 

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So now, that's the same as saying, 
t is equal to 1,000 / 4.35 five, this is 

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approximately 230 minutes. 
230 minutes is 3 hours, 50 minutes. 

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[MUSIC] 

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At this point, 3 hours and 50 minutes has 
gone by. 

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If we check the cube, [MUSIC] we see it's 
right at a 1,000 milliliters. 

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[MUSIC]